This article is within the scope of WikiProject Electrical engineering, a collaborative effort to improve the coverage of
Electrical engineering on Wikipedia. If you would like to participate, please visit the project page, where you can join
the discussion and see a list of open tasks.Electrical engineeringWikipedia:WikiProject Electrical engineeringTemplate:WikiProject Electrical engineeringelectrical engineering articles
If the word "ampacity" is only used in the US, the article should state this.
Otherwise, the article should be edited to be less US-centric (is there an international standard about ampacity?)
Jushi11:27, 30 November 2006 (UTC)reply
the National Electrical Code, published by the National Fire Protection Association, is used throughout the world. —The preceding
unsigned comment was added by
64.24.209.223 (
talk •
contribs).
While i'm sure there are places outside the US that use the NEC "throughout the world" is almost certainly a massive exaggeration. I don't have a specific source for what regulations are used in what countries but
http://upload.wikimedia.org/wikipedia/commons/d/db/WorldMap_Voltage%26Frequency.png makes it pretty obvious that the reach of US electrical standards is mostly limited to america.
Afaict electrical standards divide into blocks, you have the US and US influenced countries using US standards (either directly or locally developed variants of them), Europeans and austrialians using the same voltages, frequencies and cable sizing system but with the details of regulations varying from country to country and many other countries following one of them (again either using the standards directly or locally derived variants).
Any electricial installation standard will standard current carrying capacity of cables. The exact rating they give to a cable type will depend on allowable temperature and what assumptions they make about cooling but in general the physics of the situation mean that similar cables will likely get similar ratings from different standards bodies.
Getting back on-topic ss a brit (who is an electrical engineering PHD student and friends with an electriciant) the only time i've ever seen the term "ampacity" is on american websites. We brits seem to just call it current carrying capacity (or just capacity when it's obvious from the context).
Plugwash (
talk)
04:14, 21 January 2011 (UTC)reply
The term (ampacity) is also used and definined by the Canadian Electrical Code but was never a real word (derived from "ampere capacity") except for the purpose of the particular codes. However, we know how English definitions aint fixed till some encyclopedia writer uses the slang for summat.
99.251.114.120 (
talk)
04:31, 13 March 2012 (UTC)reply
lede obtuse?
The lede seems a bit hard to understand. Can't it start with defining ampacity as "the current-handling capacity of a wire or device," and define situational constraints (temperature, etc.) later?
jhawkinson09:16, 22 June 2007 (UTC)reply
Temperature rise in bare wire in free air
This article is too limited. It should at least have links to info about the temp rise in various bare wires in free air at various currents.
-
71.174.184.42 (
talk)
23:21, 20 May 2009 (UTC)reply
formulae needed
it should be possible to make quantitative predictions of the current carrying capacity, if you know the parameters. please supply formulae --
99.233.186.4 (
talk)
18:25, 2 March 2010 (UTC)reply
Difference between rated current and current rating
"However the tolerance of short-term overcurrent is near zero for semiconductor devices". 'Tolerance' is quite ambiguous here. If it means 'current reserve', not 'margin of error' - then it's true for bipolar transistors, and not true for diodes and power FETs. These are always rated for both continuous and short-term surge currents (the latter for specific test conditions). Quite often, the weakest link is not the semiconductor itself, but the metal leads - so, in the end, they aren't much different from bare wire.
"as their thermal capacities are extremely small..." - that's right. But electric pulses are short, milliseconds or less, so surge-to-continuous ratio can be quite high.
"...it is not necessary to know the current limit to design a system" - big mistake. Systems, unlike standalone parts ("lightbulb holders"), inevitably contain connecting wire ... back to square one.
Retired electrician (
talk)
03:16, 11 September 2018 (UTC)reply
This article is within the scope of WikiProject Electrical engineering, a collaborative effort to improve the coverage of
Electrical engineering on Wikipedia. If you would like to participate, please visit the project page, where you can join
the discussion and see a list of open tasks.Electrical engineeringWikipedia:WikiProject Electrical engineeringTemplate:WikiProject Electrical engineeringelectrical engineering articles
If the word "ampacity" is only used in the US, the article should state this.
Otherwise, the article should be edited to be less US-centric (is there an international standard about ampacity?)
Jushi11:27, 30 November 2006 (UTC)reply
the National Electrical Code, published by the National Fire Protection Association, is used throughout the world. —The preceding
unsigned comment was added by
64.24.209.223 (
talk •
contribs).
While i'm sure there are places outside the US that use the NEC "throughout the world" is almost certainly a massive exaggeration. I don't have a specific source for what regulations are used in what countries but
http://upload.wikimedia.org/wikipedia/commons/d/db/WorldMap_Voltage%26Frequency.png makes it pretty obvious that the reach of US electrical standards is mostly limited to america.
Afaict electrical standards divide into blocks, you have the US and US influenced countries using US standards (either directly or locally developed variants of them), Europeans and austrialians using the same voltages, frequencies and cable sizing system but with the details of regulations varying from country to country and many other countries following one of them (again either using the standards directly or locally derived variants).
Any electricial installation standard will standard current carrying capacity of cables. The exact rating they give to a cable type will depend on allowable temperature and what assumptions they make about cooling but in general the physics of the situation mean that similar cables will likely get similar ratings from different standards bodies.
Getting back on-topic ss a brit (who is an electrical engineering PHD student and friends with an electriciant) the only time i've ever seen the term "ampacity" is on american websites. We brits seem to just call it current carrying capacity (or just capacity when it's obvious from the context).
Plugwash (
talk)
04:14, 21 January 2011 (UTC)reply
The term (ampacity) is also used and definined by the Canadian Electrical Code but was never a real word (derived from "ampere capacity") except for the purpose of the particular codes. However, we know how English definitions aint fixed till some encyclopedia writer uses the slang for summat.
99.251.114.120 (
talk)
04:31, 13 March 2012 (UTC)reply
lede obtuse?
The lede seems a bit hard to understand. Can't it start with defining ampacity as "the current-handling capacity of a wire or device," and define situational constraints (temperature, etc.) later?
jhawkinson09:16, 22 June 2007 (UTC)reply
Temperature rise in bare wire in free air
This article is too limited. It should at least have links to info about the temp rise in various bare wires in free air at various currents.
-
71.174.184.42 (
talk)
23:21, 20 May 2009 (UTC)reply
formulae needed
it should be possible to make quantitative predictions of the current carrying capacity, if you know the parameters. please supply formulae --
99.233.186.4 (
talk)
18:25, 2 March 2010 (UTC)reply
Difference between rated current and current rating
"However the tolerance of short-term overcurrent is near zero for semiconductor devices". 'Tolerance' is quite ambiguous here. If it means 'current reserve', not 'margin of error' - then it's true for bipolar transistors, and not true for diodes and power FETs. These are always rated for both continuous and short-term surge currents (the latter for specific test conditions). Quite often, the weakest link is not the semiconductor itself, but the metal leads - so, in the end, they aren't much different from bare wire.
"as their thermal capacities are extremely small..." - that's right. But electric pulses are short, milliseconds or less, so surge-to-continuous ratio can be quite high.
"...it is not necessary to know the current limit to design a system" - big mistake. Systems, unlike standalone parts ("lightbulb holders"), inevitably contain connecting wire ... back to square one.
Retired electrician (
talk)
03:16, 11 September 2018 (UTC)reply